Coffee's off the hook for causing cancer, may even reduce risk

Go ahead, have another cup of coffee, the World Health Organization says it’s OK. In a reversal of its 1991 assessment, the WHO has now cleared coffee of carcinogenic properties, according to Ars Technica. And it gets better than that — coffee may even reduce some cancer risks. The news is not so great, however, for people who drink maté or other beverages, even water, at temperatures 140 degrees Fahrenheit or higher.

The International Agency for Research on Cancer (IARC), a group of 23 scientists who make up a WHO Working Group, released the results of their examination of scientific studies about the potential cancer risks of coffee, maté, and very hot drinks. The IARC work is a study of studies, also known as a meta-analysis, which takes into account most or all of the research and scientific studies on a given subject, in this case, the carcinogenic effects of coffee and other drinks.

The key finding of the IARC reads, “The Working Group found no conclusive evidence for a carcinogenic effect of drinking coffee. However, the experts did find that drinking very hot beverages (140 degrees or higher) probably causes cancer of the oesophagus in humans. No conclusive evidence was found for drinking maté at temperatures that are not very hot.”

The primary focus of the study was the relationship between esophageal cancer and various drinks. In 1991 the WHO said that coffee was “possibly carcinogenic to humans.” Now, coffee’s classification has been changed to “not classifiable,” meaning the scientists found no relationship. Very hot beverages, however, are now classified as “probably carcinogenic,” which is an even stronger warning than the earlier (incorrect) message about coffee.

The scientists also looked at the relationship of coffee and other types of cancer and here the news gets even better. “Many epidemiological studies showed that coffee drinking had no carcinogenic effects for cancers of the pancreas, female breast, and prostate, and reduced risks were seen for cancers of the liver and uterine endometrium.” So not only is coffee essentially cleared for causing cancer in other organs, it looks like it can help prevent liver and uterine cancer.